renderingcontext.html

Geotools是一个开源的Java GIS工具包,可利用它来开发符合标准的地理信息系统。Geotools提供了OGC(Open Geospatial Consortium)规范的一个实现来作为他们的

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&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Declares that an area has been painted. </TD>
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<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>&nbsp;<A HREF="http://java.sun.com/j2se/1.4/docs/api/java/awt/geom/AffineTransform.html" title="class or interface in java.awt.geom">AffineTransform</A></CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../../org/geotools/display/canvas/RenderingContext.html#getAffineTransform(org.opengis.referencing.crs.CoordinateReferenceSystem, org.opengis.referencing.crs.CoordinateReferenceSystem)">getAffineTransform</A></B>(CoordinateReferenceSystem&nbsp;sourceCRS,
                   CoordinateReferenceSystem&nbsp;targetCRS)</CODE>

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&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Returns an affine transform between two coordinate reference systems. </TD>
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<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>&nbsp;<A HREF="http://java.sun.com/j2se/1.4/docs/api/java/awt/Graphics2D.html" title="class or interface in java.awt">Graphics2D</A></CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../../org/geotools/display/canvas/RenderingContext.html#getGraphics()">getGraphics</A></B>()</CODE>

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&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Returns the graphics where painting occurs. </TD>
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<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>&nbsp;MathTransform</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../../org/geotools/display/canvas/RenderingContext.html#getMathTransform(org.opengis.referencing.crs.CoordinateReferenceSystem, org.opengis.referencing.crs.CoordinateReferenceSystem)">getMathTransform</A></B>(CoordinateReferenceSystem&nbsp;sourceCRS,
                 CoordinateReferenceSystem&nbsp;targetCRS)</CODE>

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&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Returns a transform between two coordinate systems. </TD>
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<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>&nbsp;<A HREF="http://java.sun.com/j2se/1.4/docs/api/java/awt/Shape.html" title="class or interface in java.awt">Shape</A></CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../../org/geotools/display/canvas/RenderingContext.html#getPaintingArea(org.opengis.referencing.crs.CoordinateReferenceSystem)">getPaintingArea</A></B>(CoordinateReferenceSystem&nbsp;crs)</CODE>

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&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Returns the painting area in the specified coordinate reference system. </TD>
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<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>&nbsp;double</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../../org/geotools/display/canvas/RenderingContext.html#getScale()">getScale</A></B>()</CODE>

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&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Returns the scale factor, or <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/Double.html#NaN" title="class or interface in java.lang"><CODE>NaN</CODE></A> if the scale is unknow. </TD>
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<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>&nbsp;boolean</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../../org/geotools/display/canvas/RenderingContext.html#isPrinting()">isPrinting</A></B>()</CODE>

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&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Returns  if the output device is a printer instead of screen. </TD>
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<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>&nbsp;void</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../../org/geotools/display/canvas/RenderingContext.html#setGraphicsCRS(org.opengis.referencing.crs.CoordinateReferenceSystem)">setGraphicsCRS</A></B>(CoordinateReferenceSystem&nbsp;crs)</CODE>

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&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Sets the coordinate reference system in use for rendering in <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/awt/Graphics2D.html" title="class or interface in java.awt"><CODE>Graphics2D</CODE></A>. </TD>
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&nbsp;<A NAME="methods_inherited_from_class_Object"><!-- --></A>
<TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY="">
<TR BGCOLOR="#EEEEFF" CLASS="TableSubHeadingColor">
<TD><B>Methods inherited from class <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/Object.html" title="class or interface in java.lang">Object</A></B></TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD><CODE><A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/Object.html#clone()" title="class or interface in java.lang">clone</A>, <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/Object.html#equals(java.lang.Object)" title="class or interface in java.lang">equals</A>, <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/Object.html#finalize()" title="class or interface in java.lang">finalize</A>, <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/Object.html#getClass()" title="class or interface in java.lang">getClass</A>, <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/Object.html#hashCode()" title="class or interface in java.lang">hashCode</A>, <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/Object.html#notify()" title="class or interface in java.lang">notify</A>, <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/Object.html#notifyAll()" title="class or interface in java.lang">notifyAll</A>, <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/Object.html#toString()" title="class or interface in java.lang">toString</A>, <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/Object.html#wait()" title="class or interface in java.lang">wait</A>, <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/Object.html#wait(long)" title="class or interface in java.lang">wait</A>, <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/Object.html#wait(long, int)" title="class or interface in java.lang">wait</A></CODE></TD>
</TR>
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<!-- ============ FIELD DETAIL =========== -->

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<TD COLSPAN=1><FONT SIZE="+2">
<B>Field Detail</B></FONT></TD>
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</TABLE>

<A NAME="objectiveCRS"><!-- --></A><H3>
objectiveCRS</H3>
<PRE>
public final CoordinateReferenceSystem <B>objectiveCRS</B></PRE>
<DL>
<DD>A snapshot of <A HREF="../../../../org/geotools/display/canvas/ReferencedCanvas.html#getObjectiveCRS()"><CODE>ReferencedCanvas.getObjectiveCRS()</CODE></A> at the time of painting. This is the
 "real world" coordinate reference system that the user will see on the screen. Data from all
 <A HREF="../../../../org/geotools/display/canvas/GraphicPrimitive2D.html" title="class in org.geotools.display.canvas"><CODE>GraphicPrimitive2D</CODE></A> must be transformed to this CRS before to be painted. Units are
 usually "real world" metres.
 <p>
 This coordinate system is usually set once for a given <A HREF="../../../../org/geotools/display/canvas/BufferedCanvas2D.html" title="class in org.geotools.display.canvas"><CODE>BufferedCanvas2D</CODE></A> and do not
 change anymore, except if the user wants to change the projection see on screen.
<P>
<DL>
<DT><B>See Also:</B><DD><A HREF="../../../../org/geotools/display/canvas/RenderingContext.html#displayCRS"><CODE>displayCRS</CODE></A>, 
<A HREF="../../../../org/geotools/display/canvas/RenderingContext.html#setGraphicsCRS(org.opengis.referencing.crs.CoordinateReferenceSystem)"><CODE>setGraphicsCRS(org.opengis.referencing.crs.CoordinateReferenceSystem)</CODE></A>, 
<A HREF="../../../../org/geotools/display/canvas/ReferencedCanvas.html#getObjectiveCRS()"><CODE>ReferencedCanvas.getObjectiveCRS()</CODE></A></DL>
</DL>
<HR>

<A NAME="displayCRS"><!-- --></A><H3>
displayCRS</H3>
<PRE>
public final CoordinateReferenceSystem <B>displayCRS</B></PRE>
<DL>
<DD>A snapshot of <A HREF="../../../../org/geotools/display/canvas/ReferencedCanvas.html#getDisplayCRS()"><CODE>ReferencedCanvas.getDisplayCRS()</CODE></A> at the time of painting. This CRS maps
 the <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/awt/Graphics2D.html" title="class or interface in java.awt">user space</A> in terms of <cite>Java2D</cite>: each "unit" is a dot
 (about 1/72 of inch). <var>x</var> values increase toward the right of the screen and
 <var>y</var> values increase toward the bottom of the screen. This CRS is appropriate
 for rendering text and labels.
 <p>
 This coordinate system may be different between two different renderings,
 especially if the zoom (or map scale) has changed since the last rendering.
<P>
<DL>
<DT><B>See Also:</B><DD><A HREF="../../../../org/geotools/display/canvas/RenderingContext.html#objectiveCRS"><CODE>objectiveCRS</CODE></A>, 
<A HREF="../../../../org/geotools/display/canvas/RenderingContext.html#setGraphicsCRS(org.opengis.referencing.crs.CoordinateReferenceSystem)"><CODE>setGraphicsCRS(org.opengis.referencing.crs.CoordinateReferenceSystem)</CODE></A>, 
<A HREF="../../../../org/geotools/display/canvas/ReferencedCanvas.html#getDisplayCRS()"><CODE>ReferencedCanvas.getDisplayCRS()</CODE></A></DL>
</DL>

<!-- ========= CONSTRUCTOR DETAIL ======== -->


<!-- ============ METHOD DETAIL ========== -->

<A NAME="method_detail"><!-- --></A>
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<TD COLSPAN=1><FONT SIZE="+2">
<B>Method Detail</B></FONT></TD>
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<A NAME="getGraphics()"><!-- --></A><H3>
getGraphics</H3>
<PRE>
public final <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/awt/Graphics2D.html" title="class or interface in java.awt">Graphics2D</A> <B>getGraphics</B>()</PRE>
<DL>
<DD>Returns the graphics where painting occurs. The initial coordinate reference system is
 <A HREF="../../../../org/geotools/display/canvas/RenderingContext.html#displayCRS"><CODE>displayCRS</CODE></A>, which maps the <cite>Java2D</cite> <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/awt/Graphics2D.html" title="class or interface in java.awt">user space</A>.
 For drawing shapes directly in terms of "real world" coordinates, users should invoke
 <code><A HREF="../../../../org/geotools/display/canvas/RenderingContext.html#setGraphicsCRS(org.opengis.referencing.crs.CoordinateReferenceSystem)">setGraphicsCRS</A>(<A HREF="../../../../org/geotools/display/canvas/RenderingContext.html#objectiveCRS">objectiveCRS</A>)</code>.
<P>
<DD><DL>
</DL>
</DD>
</DL>
<HR>

<A NAME="getPaintingArea(org.opengis.referencing.crs.CoordinateReferenceSystem)"><!-- --></A><H3>
getPaintingArea</H3>
<PRE>
public <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/awt/Shape.html" title="class or interface in java.awt">Shape</A> <B>getPaintingArea</B>(CoordinateReferenceSystem&nbsp;crs)
                      throws TransformException</PRE>
<DL>
<DD>Returns the painting area in the specified coordinate reference system. If the CRS
 is <A HREF="../../../../org/geotools/display/canvas/RenderingContext.html#displayCRS"><CODE>displayCRS</CODE></A>, then this method will usually returns the widget's bounds
 (<A HREF="http://java.sun.com/j2se/1.4/docs/api/java/awt/Component.html#getBounds()" title="class or interface in java.awt"><CODE>Component.getBounds()</CODE></A>).
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>crs</CODE> - The coordinate reference system (usually one of <A HREF="../../../../org/geotools/display/canvas/RenderingContext.html#displayCRS"><CODE>displayCRS</CODE></A> or
         <A HREF="../../../../org/geotools/display/canvas/RenderingContext.html#objectiveCRS"><CODE>objectiveCRS</CODE></A>).
<DT><B>Returns:</B><DD>The painting area in terms of the specified CRS.
<DT><B>Throws:</B>
<DD><CODE>TransformException</CODE> - if the painting area can be expressed in the specified CRS.</DL>
</DD>
</DL>
<HR>

<A NAME="setGraphicsCRS(org.opengis.referencing.crs.CoordinateReferenceSystem)"><!-- --></A><H3>
setGraphicsCRS</H3>
<PRE>
public void <B>setGraphicsCRS</B>(CoordinateReferenceSystem&nbsp;crs)
                    throws TransformException</PRE>
<DL>
<DD>Sets the coordinate reference system in use for rendering in <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/awt/Graphics2D.html" title="class or interface in java.awt"><CODE>Graphics2D</CODE></A>. Invoking
 this method do not alter the current state of any canvas or GO-1 graphic objects. It is
 only a convenient way to <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/awt/Graphics2D.html#setTransform(java.awt.geom.AffineTransform)" title="class or interface in java.awt">set the affine transform</A> in
 the current <cite>Java2D</cite> <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/awt/Graphics2D.html" title="class or interface in java.awt"><CODE>Graphics2D</CODE></A> handle, for example in order to alternate
 rendering mode between geographic features and labels. The specified coordinate reference
 system (the  argument) is usually (but not limited to) one of
 <A HREF="../../../../org/geotools/display/canvas/RenderingContext.html#objectiveCRS"><CODE>objectiveCRS</CODE></A> or <A HREF="../../../../org/geotools/display/canvas/RenderingContext.html#displayCRS"><CODE>displayCRS</CODE></A> values.
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>crs</CODE> - The CRS for the <A HREF="../../../../org/geotools/display/canvas/RenderingContext.html#getGraphics()"><CODE>Java2D graphics handle</CODE></A>.
<DT><B>Throws:</B>
<DD><CODE>TransformException</CODE> - if this method failed to find an affine transform from the
         specified CRS to the device CRS.<DT><B>See Also:</B><DD><A HREF="../../../../org/geotools/display/canvas/RenderingContext.html#getGraphics()"><CODE>getGraphics()</CODE></A>, 
<A HREF="../../../../org/geotools/display/canvas/RenderingContext.html#getAffineTransform(org.opengis.referencing.crs.CoordinateReferenceSystem, org.opengis.referencing.crs.CoordinateReferenceSystem)"><CODE>getAffineTransform(org.opengis.referencing.crs.CoordinateReferenceSystem, org.opengis.referencing.crs.CoordinateReferenceSystem)</CODE></A>, 
<A HREF="http://java.sun.com/j2se/1.4/docs/api/java/awt/Graphics2D.html#setTransform(java.awt.geom.AffineTransform)" title="class or interface in java.awt"><CODE>Graphics2D.setTransform(java.awt.geom.AffineTransform)</CODE></A></DL>
</DD>
</DL>
<HR>

<A NAME="getAffineTransform(org.opengis.referencing.crs.CoordinateReferenceSystem, org.opengis.referencing.crs.CoordinateReferenceSystem)"><!-- --></A><H3>
getAffineTransform</H3>